Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations only declare readOnly=false, openWorld=true, destructive=false; the description goes well beyond them by stating that nothing is sent to the contact, that the return value is contact_id, that duplicates cannot be prevented by the API, that each call is confirmed by default and can be toggled off, and that a Cotlet API key with app access is required. This is unusually rich side-effect and auth disclosure.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Front-loaded with the core action and return value, and each sentence carries distinct information. The confirmation guidance is split across two sentences ('By default you confirm each call' and 'confirm with the user before each call'), which is mild redundancy.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Covers the action, return value, prerequisite, duplicate risk, confirmation default, and auth requirement despite there being no output schema. The boilerplate 'Reaches other people: confirm with the user' sits slightly awkwardly against 'It sends nothing to the person', leaving a small ambiguity for the agent.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so the schema already documents all seven fields including the client/supplier/both enum. The description echoes the kind values but adds no format or constraint detail beyond the schema, so the baseline 3 applies.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource ('Add a client, a supplier or both to Contactos', 'Creates a contact ... returns its contact_id') and distinguishes itself from the sibling read tool by naming list_contacts as a prerequisite. An agent can identify exactly what this does without opening the schema.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Gives an explicit prerequisite ('Call list_contacts first') and a concrete reason (Alegra permits duplicate names, and duplicates must be removed by hand). It also states the default confirmation behavior. It stops short of naming when-not-to-use cases, but the routing context is clear.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.